Which came first, the chicken or the egg?
At first glance, this seems like a reasonable question. But most questions have hidden assumptions, and this question has tons of them. And as it turns out, most of the assumptions are incorrect – meaning that the question – as it is usually asked or understood – is actually meaningless.
The question assumes that (a) chickens and eggs have existed continuously, without change, for a long period of time (b) that chickens (vaguely defined!) lay eggs (also vaguely defined!), and (c) that eggs hatch into chickens.
Problem? None of these assumptions are true. They only appear to be true because people only look at chickens and eggs over a very short period of time (perhaps weeks, a year, or when reading books, thinking back over the last 5000 years.)
But birds and their ancestors have been continuously changing for millions of years – and so has the way that their ancestors reproduced. The first chickens… may not even have been chickens, but rather some other form of bird that no longer exists. And those earlier birds are descendants of a branch of the dinosaur family tree; and those early dinosaurs are a branch of the reptile family tree. And over very long, deep periods of time, the way that these organisms reproduced has actually changed!
In fact, the first eggs developed millions of years before anything we even know as birds existed.